Device for measuring relative velocities

ABSTRACT

An electronic device for determining the relative speed between two units-vehicles or the like-by utilizing the Doppler effect. A transmitter would be located in one vehicle to transmit on a given frequency but also to transmit an encoded number corresponding to the transmitting frequency. The receiver, by detection of the shift between the coded number and the received frequency would determine the relative speed between the transmitter and the receiver.

United States Patent Inventor Robert A. Higgins Apt. 34 Ilawerysh Apts.,Brookings, S. Dak.

Appl. No. 862,742

Filed Oct. 1, I969 Patented Sept. 14, I971 DEVICE FOR MEASURING RELATIVEVELOCI'I'IES [56] References Cited UNITED STATES PATENTS 2,770,795 1H1956 Peterson 340/3 Primary Examiner- Rodney B. Bennett, Jr. AssistantExaminer-R. Kinberg Attorney-Lucas J. De Koster ABSTRACT: An electronicdevice for determining the relative speed between two units-vehicles orthe likeby utilizing the Doppler effect. A transmitter would be locatedin one 8 Claims: Drawing Figs vehicle to transmit on a given frequencybut also to transmit US. Cl 343/112 S an encoded number corresponding toV the transmitting Int. CL G015 9/44 frequency. The receiver, bydetection of the shift between the Field ofSearch 343/8, 112 codednumber and the received frequency would determine 5 the relative speedbetween the transmitter and the receiver.

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VELOCITY COMPUTER [/9 FREQUENCY COUNTER PAT ENTEU SEPI 4 l97| VI H u M aD V W m M w W M M R Y R c A ET 0 L UN c l l l I l l I f DISPLAY andCONTROL UNIT VELOCITY COMPUTER OEMODULATOR [/9 FREQUENCY COUNTERAMPLIFIER Robert A. Higgins INVENTOR.

His A" DEVICE FOR MEASURING RELATIVE VELOCITIES BACKGROUND AND SUMMARYOF THE INVENTION T s invention pertains to speed detection units andmore particularly to a device for indicating the relative speed betweentwo units by using the Doppler effect. The possibility of momentaryerrors because of instability in the system is averted.

Many devices have been proposed, and some used to determine the speed ofa vehicle. Some of these may be appropriate also to determine the speedof approach of one vehicle relative to another. The usual system is aradar-type system in which the difference in frequency between thatreflected from the moving object and that reflected from a fixed objector between the reflection from the moving object and the transmittedsignal was sensed and converted into a velocity figure which could beread out and understood in standard velocity measurement.

These systems have various shortcomings. Momentary instability can causevariations between the frequency transmitted at the time the reflectedwave was sent out and the frequency at the time of reception. Radar isnonselective, and either a highly directional antenna must be used, orthere must be some other means of identifying the object from which thesignal is reflected. Without that, there is no possibility of knowingwhat speed is being measured.

My device eliminates even momentary errors and since normally thereceiver will be carried by one unit and the transmitter by another, theidentification is unnecessary except as between the various units andnot between all possible objects. To that extent, my device may haveutilization in collision avoidance systems as well as simply velocitymeasurement.

FIGURES FIG. 1 is a diagrammatic sketch of the functional units utilizedin the transmitter, and

FIG. 2 is a similar diagram of the units in the receiver.

DESCRIPTION Briefly my invention comprises a device by which velocitymay be determined by means of transmitting means in one vehicle adaptedto transmit an encoded signal including both the identification of thevehicle and the instantaneous frequency at which the signal is beingtransmitted, and receiving means either in another vehicle or in astationary location which can compare the actual received frequency withthe encoded transmitted frequency to indicate velocity and alsodistinguish the identity signal.

More specifically and referring to the drawings I provide fortransmitting unit to be carried by the vehicle. This unit is showndiagrammatically in FIG. 1 and includes an oscillator which generates acarrier wave. In the present state of the art this would almostundoubtedly be an electromagnetic wave in the range of radiofrequencies. However, I envision the possibility of using a beam in therange of visible light frequencies or perhaps a compressive wave similarto sound waves.

The carrier signal is then divided with one part being sent through afrequency determining unit ill. This unit determines the actualfrequency generated and feeds that information to an encoding unit 12.It will be apparent to those skilled in the art that any of the severaldevices now known and which are able to determine frequency may be usedand that throughout this application the terms counter or frequencycounter" may apply to any such device. The encoder 12 may also receiveinformation from an identification unit 13. The identifier is notnecessary, but can provide useful information concerning the identity ofthe vehicle carrying the transmitter.

The encoder l2 translates the information received from the counter I1and the identifier 13 into suitable analog or digital form, and imposesthis information on the carrier wave by suitable type of modulation.

The second part of the generated signal is sent through a delay device14. The delay here is of the same length as the time required for thefirst portion of the signal to pick up the encoded information from theencoder 12 through the counter 11 and from the identifier 13. Thus, thetwo branches of the original signal are again united in the modulator15. Such use of the delay unit 14 makes certain that instantaneousshifts in frequency from the oscillator 10 or instability in theoscillator do not affect the accuracy of the device. Since the wavewhich is counted is a portion of exactly the same wave as transmitted,the encoded number will still be the correct frequency as actuallytransmitted, and the apparent shift between the encoded number andreceived frequency will provide an accurate measure.

The transmitting antenna 16 or transducer may be properly chosen for thetype of wave used by the device. Such choice is well within the abilityof anyone skilled in the art.

The receiving device is shown diagrammatically in FIG. 2. This device isadapted to receive the signal at a receiving antenna 17 or transducerand feed it into the amplifier 18. At this point, the received signal isagain divided with one branch going through a counter 19 where thefrequency of the received signal is determined.

The other branch of the signal is fed into a demodulator 20 or detectorwhich distinguishes the coded information and also separates the codedfrequency number from the identification signal. The frequency number isfed into a velocity computer 21. This computer also receives theinformation from the counter 19 again with proper time phasing so thatthe counted signal is a part of the identical signal carrying theencoded frequency number. The computer 21 by comparing the countedsignal with the encoded frequency number determines the relativevelocity between the sending unit and the receiving unit in the samemanner as a radar unit might.

The display unit 22 receives the information from the computer 21 as tospeed and from the demodulator 20 as to identity and provides fordisplay of the information. This display would ordinarily be a visualdisplay on a dial or the like, but could well be audible or even tactileif desired. For example, if the sending unit were a stationary unitalong a highway and the receiver were required to be in any automobileusing that highway, the device could be built to induce a mild electricshock through the seat of the car to any driver who exceeded a certainspeed, or it could sound an audible alarm for excess speed.

It is obvious that my device can be used to determine the relative speedbetween a stationary object such as a receiver unit mounted alongside ahighway and a moving vehicle carrying a transmitter. It could also beused to determine relative speeds between a moving police car andanother moving car. In this latter case, the speed of the police carcould also be fed into the computer 21 to determine the actual speed ofthe automobile on the highway as well as the relative speeds. In eitherof these events, the installation of the transmitter in the oneautomobile would be essential. This equipment might be required by lawon all roads, or perhaps only on certain limited use highways.

However, I see alternate possibilities of utility for this system. Forexample, in aircraft or spacecraft the device combined with a directionindicating device could be used for collision avoidance systems. Thesame utility is available to maritime vessels.

Thus, either separately or in combination with other systems, I haveprovided a very useful and novel device.

I claim:

1. A device for measuring relative speed between two units comprising:

a. Oscillator means to generate a carrier wave,

b. Means connected to said oscillator means to receive impulses of saidwave and measure and encode the frequency thereof and to impose suchencoded frequency on said wave and to transmit it, and

c. Receiver means to receive said wave including means to distinguishsaid encoded frequency, means to measure the received frequency, both ofsaid last-named means being connected to computer means, said computermeans being adapted to compare the encoded frequency with the receivedfrequency to compute the relative velocity therefrom.

2. The device of claim 1 in which said means connected to saidoscillator means includes dual branches, one branch including frequencymeasuring and encoding means and the other branch including delay meanswhereby the encoded frequency is imposed on waves generatedsimultaneously.

3. The device of claim 2 in which identification means is also connectedto the encoding means whereby coded identification is also imposed onsaid wave.

4. The device of claim 1 in which said receiver includes display meanswhereby said velocity is displayed to an operator.

5. The device of claim 3 in which said receiver includes a display meanswhereby said velocity and identification is made evident to an operator6. The method of measuring relative velocity between a wave source and areceiver which comprises generating a carrier wave, imposing the countedfrequency of said wave as encoded intelligence on said wave andcomparing the encoded intelligence with the counted frequency of thewave as received by said receiver.

7. The method claimed in claim 6 in which said counted frequency isimposed on the wave generated simultaneously with the wave whosefrequency is counted.

8. The method of claim 6 in which identification information is alsoimposed on said wave and discriminated by said receiver.

1. A device for measuring relative speed between two units comprising:a. Oscillator means to generate a carrier wave, b. Means connected tosaid oscillator means to receive impulses of said wave and measure andencode the frequency thereof and to impose such encoded frequency onsaid wave and to transmit it, and c. Receiver means to receive said waveincluding means to distinguish said encoded frequency, means to measurethe received frequency, both of said last-named means being connected tocomputer means, said computer means being adapted to compare the encodedfrequency with the received frequency to compute the relative velocitytherefrom.
 2. The device of claim 1 in which said means connected tosaid oscillator means includes dual branches, one branch includingfrequency measuring and encoding means and the other branch includingdelay means whereby the encoded frequency is imposed on waves generatedsimultaneously.
 3. The device of claim 2 in which identification meansis also connected to the encoding means whereby coded identification isalso imposed on said wave.
 4. The device of claim 1 in which saidreceiver includes display means whereby said velocity is displayed to anoperator.
 5. The device of claim 3 in which said receiver includes adisplay means whereby said velocity and identification is made evidentto an operator.
 6. The method of measuring relative velocity between awave source and a receiver which comprises generating a carrier wave,imposing the counted frequency of said wave as encoded intelligence onsaid wave and comparing the encoded intelligence with the countedfrequency of the wave as received by said receiver.
 7. The methodclaimed in claim 6 in which said counted frequency is imposed on thewave generated simultaneously with the wave whose frequency is counted.8. The method of claim 6 in which identification information is alsoimposed on said wave and discriminated by said receiver.